Compressor fridge at +4Deg C will run for 5 days from a cheap 120Ah LA battery.
To get a 120Ah LA battery from 50% capacity back to 100% takes 23 hours with one of the chargers that fleck2 describes.
To ensure you don't run your LA battery to below 50% capacity, keep an eye on the voltage, plenty of charts on google, you just need a pocket multimeter to check the voltage.
Better still, get a battery monitor, I use the Aili Capacity tester TR16, got one from China recently just £28 but will help keep my battery in tip top condition, and prevents me from running it to below 50% capacity.
Brilliant thank you everyone!
Actually, if I got a lithium battery and a deccompressor fridge...... wouldn't need a solar panel.....is that correct...I know these batteries are pricey.....but it seems easier in the longer term?
To keep things sensible price wise, you are better of getting a cheap 120Ah LA battery, for around £90 that will keep a compressor fridge going for 5 days without damaging the battery, as it will be down to about 50% capacity, then a cheap Aldi charger will get it back to 100% in around 23 hours.
In fact if you add in a 100 watt solar panel and MPPT controller, so say another £120 that would keep the battery going almost indefinitely. so there's £210 add another £290 for the compressor fridge, and that your budget £500.
You can alway get a LiFePo4 100Ah battery when they come cheaper in a few years time, by then your 120Ah LA battery will be about ready for replacement in any case.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.